Feature

DARPA Challenge

A titanium mesh sphere is positioned in an ORNL lab to be crushed--destructive testing to obtain parameters for DARPA's $50,000 DMACE Challenge.

OAK RIDGE, Tenn.,
Dec. 10, 2010
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The crushing of 180 digitally manufactured (DM) titanium mesh spheres has culminated in a $50,000 DARPA prize for a University of California at Santa Barbara team, who came up with the most accurate predictive model of the components' properties.

The competition, which subjected spheres produced at the Department of Energy's Oak Ridge National Laboratory in Tennessee and polymer cubes produced at the Navy Postgraduate School in Monterey, Calif., to destructive testing, were part of DARPA's Digital Manufacturing Analysis, Correlation and Estimation (DMACE) Challenge to showcase the potential of digital manufacturing of advanced materials.

Dr. Leo Christodoulou, director of the Defense Sciences Office, stated, "DARPA and its service chiefs' fellows also established a significant repository of open-source data for digital manufacturing. This collection of open-source data, if expanded, has the potential for accelerating the understanding of DM processes with regard to their output products and may enable processes leading to the certification and approval of DM components for use in military systems."

The UC Santa Barbara team used machine input parameters published by the organizers to derive models to predict the failure strength of the titanium spheres and polymer cubes. The aim of the program is to build awareness of the potential of free-form manufacturing with advanced materials and computer-aided design and simulation. The ability to predict the properties and qualities of parts produced by these processes will help reduce the costs, spark innovation and, ultimately, revitalize U.S. industry.

"This is where advanced manufacturing technology is headed, and Oak Ridge National Laboratory is leading the way," Lt. Col. Tom Westen said.

ORNL's titanium spheres were fabricated by a process called electron-beam deposition in which a titanium-based powder is fused with an electron beam to produce a component from a computer-aided drawing. The design is fabricated in successive layers until the component is completed.

The resulting DMACE Challenge product from the ORNL advanced materials processing laboratory is a hollow, golf-ball-sized mesh sphere. Although nearly impossible to make with standard manufacturing methods, the ORNL lab produced more than 200 of the spheres for the competition, in which 10 sets of 18 were subjected to crushing to determine the parameters. Similarly, polymer cubes were produced at the Navy's California facility.

"Titanium has desirable strength and weight properties, but conventional manufacturing practices make is cost-prohibitive for many applications," said Craig Blue, who leads ORNL's energy materials program. "With these advanced fabrication technologies, and with programs such as the DMACE Challenge, we want to demonstrate that components that have been prohibitively costly and difficult are now within universal application in the field."

The DARPA service chiefs fellows came up with the DMACE Challenge idea at the beginning of their three-month fellowship, and partnered with ORNL to fast-track the competition to completion. Based on technologies and techniques developed under DOE's Industrial Technologies Program, ORNL was able to deliver the spheres for the competition.

"We've really been impressed with how fast they made it happen, from concept to reality in eight weeks," said Lt. Col. David Rhoads, one of the DARPA service chiefs fellows from the four branches of the service.

"The speed in which they delivered the spheres from computer drawing to finished component is critical, because solutions to problems encountered by soldiers in the field need to be found in days, not weeks, months or years," Rhoads said.

Details of the DMACE competition are on the DARPA website, www.dmace.net.